June 7, 2012 -- A new study shows that the drug Actemra may be a more effective treatment for
rheumatoid arthritis than the drug Humira when the medications are used by themselves.

Both medications are in a class called biologics, which are designed to inhibit parts of the immune system that cause inflammation, a central feature of rheumatoid arthritis. The two drugs, though, work in slightly different ways.

Actemra works by inhibiting the chemical signal interleukin-6 (IL-6). Humira blocks tumor necrosis factor-alpha (TNF-a). Most people who take either drug do so in combination with other disease-modifying medications, like methotrexate.

But about a third of people who take the drugs can't take methotrexate, says Jeffrey Curtis, MD, MPH, a rheumatologist and assistant professor of medicine at the University of Alabama at Birmingham, where he also directs the Arthritis Clinical Intervention Program.

"That's the importance of this study. If you have somebody who can't or won't tolerate methotrexate or other DMARDs [disease-modifying antirheumatic drugs], which biologic should we pick?" Curtis was the lead investigator for the study in the U.S. He has also been a paid consultant for Roche, the maker of Actemra, and other companies that make arthritis drugs. The study was funded by Roche.

Patients Saw Greater Improvement on Actemra

In a head-to-head comparison study that included 325 people with rheumatoid arthritis (RA), nearly 40% of those taking Actemra went into remission, compared to just over 10% of the Humira group. In addition, over half on Actemra had low disease activity, while fewer than 20% of those on Humira saw this degree of improvement.

Disease activity takes into account the number of swollen and tender joints a person with RA has as well as levels of body-wide inflammation, which are measured by blood tests.

Curtis points out that while those numbers look pretty dramatic, by other measures, which mostly gauge a patient's symptoms and how they're functioning, the differences were less clear-cut.

"If you say to patients, you can choose one drug or the other and the patient says, 'Well how much better am I going to get?' You could say, 'You know, you may have a couple fewer tender or swollen joints."

Something else patients need to consider, he says, is the way the drugs are given. Humira is a shot patients can give themselves at home twice a month. Actemra requires a monthly visit to a doctor's office for an infusion. That can be challenging for people who can't take time off from work or who have to travel a long way to get to a doctor's office.

Side effects between the two study groups were about equal, researchers say.

Humira Manufacturer Responds

Abbott, the company that makes Humira, said the study results were likely skewed because of the design of the trial, which used the maximum dose of Actemra but the minimum dose of Humira. In the study, 40 milligrams of Humira were given every other week. That same dose can be given weekly. "The results may be biased," says Derin Denham, senior manager of public affairs for Abbott.

Curtis says study participants were allowed to escalate their Humira dose, though they weren't required to.

He says in the real world, most doctors and patients don't opt for a weekly dose of Humira since it doesn't offer much more benefit but doubles the already hefty cost of the drug. The findings were presented at the annual meeting of the European League Against Rheumatism (EULAR) in Berlin, Germany.

Study Limitations

"The study results are very solid. The numbers here are impressive. But when you get down to the details that patients care about, both patient groups are getting a lot better, but the Actemra group gets a bit better," Curtis says.

"I think some of those intangibles like a twice-a-month injection you can give yourself versus an IV infusion, I think those start to weigh in," he says.

The other important caveat, Curtis says, is that the study offers no information about how the drugs work when used in combination with other DMARDs, like methotrexate.

"It's always going to be better to use methotrexate with either of these two drugs than to use either of these biologics by themselves," he says.

These findings were presented at a medical conference. They should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.